Island Forge: Kajiba Kanagu – Crossed Heart Forge

An overview of kanagu (hardware), both made and found, to add to the island kajiba series of photo essays, documenting the preparation, construction, and set up of a simple swordsmith style kajiba (鍛冶場, forge building) from the ground up. The main inspiration for aesthetic, form, and technique is the humble utilitarian Japanese inaka naya (納屋) style of a century ago.

Door Hinges

These simple strap and butterfly hinges were made at the time the doors were built for the former workshop. The doors were built in late 2011 from reclaimed ship lap and other scrap wood, clinch-nailed together, and braced with a hand chiseled mortise. The hinges are mounted to the door with hand forged nails, clinched over on the back. When the new building was ready the old doors were installed on it.

Freshly forged from hot rolled steel stock.

Hinges installed on the newly made doors in late 2011.

Doors and hinges reinstalled on the timberframe kajiba in early 2019.

View of the inside of the door showing the joinery and clinched nails.

Kasugai Staple Nails

Kasugai (角鎹) are large staple shaped nails that are used to tie joints, often in roof structures. Several are used for the front of the roof beam and other places where joints could loosen over time. The legs are just slightly splayed so the joint is pulled tight as they are driven in. In this case they are forged from 5mm square steel and are about 120mm wide with 35mm legs.

Close up of kasugai staple nail as used in Japanese timber frame.

Staple nail tying front beam down to protect from wind and weather damage.

Sliding Door Latch

Nijiriguchi (躙口) is a small opening such as might be used as a tea house entrance. In this case the sliding door is designed to provide ventilation and a garden view while forging. An ancient hook latch dug up from the earth during construction serves as a nijiriguchi kakegane (躙口掛金) which locks the sliding door in place when it is closed.

The hook is on the door and the eye on the inside of the frame.

Outside view while the forge is in operation.

Outside view of the nijiriguchi door when closed.

Tsurikanagu Brackets

Light control on the south windows is facilitated by split cedar exterior shutters that swing upwards (shitomibame 蔀羽目) to create shade even when opened. They can be propped open at various angles or hung from hooks (tsurikanagu 蔀戸吊金具) above in the style of shitomido (蔀戸) to form an awning that keeps direct light from the workshop.

A shorter hook holds the shutter almost horizontally but allows rain to run off.

The hook is attached to an eye in the roof joist.

Hook can be taken down by hand and used on the other shutter for a different length.

Default setting opens both shutters equally at a low angle. Shiageba in the background.

Inside view with shutter held partly open.

A slight opening allows some airflow but keeps the shop relatively dim.

At any setting the shutters provide shade from direct south light.

Interior Bolt

The interior sliding bolt keeps the secondary door securely closed when not in use. Made from scrap steel, the plate is about 2″ wide by 1/8″ thick, the bolt is 1/2″ round, the collars 1/4″ round, and the stoppers 5/16″ square. The plate is slightly countersunk and all parts filed to form a shallow shoulder and then riveted from the back. Other than making the bolt handle, most of the work was done cold (filing, bending, drilling, riveting).

The lower stopper keeps the bolt from coming out no matter where it is turned.

Closed position.

Open position.

Installed on the door, unlocked position.

Locked position, there is a slight lip peened on the stopper so it cannot be turned without lifting.

Exterior Bolt

Based on an antique Japanese design, this bolt acts as a hasp as well as a bolt or bar to secure the two doors together against the weather. The hasp can be held down with a hook, stick, or padlock.

Double headed nails with their top heads cut off were set into countersunk depressions on the back of the plate and riveted from the front. To install, the nails were inserted into pre-drilled holes in the wood and clinched over on the back of the doors. All materials were scrap from around the workshop, the plate is about 2″ wide by 1/8″ thick, the bolt is 1/2″ round, and the hasp and handle 1/4″ round. Holes were drilled with the hand cranked post drill.

Riveting the mounting pins before installing the bolt and handle.

Bolt is now trapped by the handle.

Open position.

Closed position. Two points of contact for the bolt on each door turns it into a bar that adds extra strength against the weather.

This design could be modified for an even longer throw reaching across almost half of each door.

Door Retaining Hooks

The existing door hook can be used for keeping the door latched while coming in and out and also doubles as a tie back to keep the door open against the wind. A small forged eye loop is nailed into the wall in order to catch it in the full open position.

Door retaining hook. Interior door pull is an antique bit.

Doors hooked in full open position.

Shiageba Kanagu

A couple of extras from the shiageba (finishing shed) door, reclaimed and made from scrap.

Simple interior door pull from scrap steel.

Sliding exterior door latch reclaimed from a farm gate in the Bethlehem Walk backlot.

Timeline

Gathering materials began in Fall 2018, site preparation in December 2018, the lumber was milled in the first week of January 2019, the frame assembled February 5th, and roofed February 7th. Yakisugi siding and tsuchikabe walls installed during March, and interior wall finishing in April. The goal was to have it operational by Summer 2019 minus a few finishing details.

Thanks to all who were involved in one way or another in helping facilitate this project, providing space, time, materials, assistance, advice, and encouragement.